1. Field of the Invention
The present invention is related to an input buffer system and a method of switching a dual-input buffer, and particularly to an input buffer system with a dual-input buffer switching function and method thereof.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating an input buffer 100 according to the prior art. The input buffer 100 includes a NOR gate 102 and an inverter 104. The NOR gate 102 has a first input terminal for receiving an input signal XCKE, a second input terminal for receiving an enable signal ENB, and an output terminal. The inverter 104 has an input terminal coupled to the output terminal of the NOR gate 102, and an output terminal for outputting a signal CKEI. When the enable signal ENB is at a logic-high voltage, a phase of the signal CKEI outputted by the inverter 104 is the same as a phase of the input signal XCKE. That is to say, when the input signal XCKE is at the logic-high voltage, the signal CKEI is also at the logic-high voltage, and vice versa. In addition, the input buffer 100 only consumes power during the signal CKEI being changed from the logic-high voltage to a logic-low voltage, or from the logic-low voltage to the logic-high voltage.
However, time required by the signal CKEI of the input buffer 100 being changed from the logic-high voltage to the logic-low voltage is different from time required by the signal CKEI of the input buffer 100 being changed from the logic-low voltage to the logic-high voltage. Therefore, if the signal CKEI is applied to a self refresh function of a synchronous dynamic random access memory (SDRAM), setup time of the synchronous dynamic random access memory may be incorrect when the synchronous dynamic random access memory enters the self refresh function.